Reinforcing bar



Patented Sept. 16, 1941 .2,256,060 s, l nEnvFoncmG BAR s -Jo'seph n. smmonaneoeava. @application March 29, 194e, serial No. 326,616

s I l 4 (cl. 'rz-111) I.' This invention i'elatesfto''v afil'einforcing bar, and;

more 'particularly' to a. twisted' reinforcing bar for use in reinforcing concrete.`

An object of this invention is to provide an improved solid, .twisted reinforcing bar.

` Anotherobject of thisinventionis to provide a solid twisted reinforcil'zfgim: having a relatively high yield .point `and"relatively low fiber stress.

Still another object'of'tbls invention is to provides. twisted reinforcing-'bar having a large effective bond area.

An additional object time invention is to form a reinforcing bar having an extremely high compression strength. *Y j A further 'object A.of this invention is to provide a solid twistedv reinforcing bar having such a cross-section that afterthe bar is tv'ris'ted to obtain a predetermined yieldl point there will be' less stress on the outer beljS. as compared with ordinary bars of equal cross-sectional areagiven Q the same amountof twist. l. Y.

A` still further object of thisinvention is to provide a solicl twisted reinforcing bai-having' Y all of the advantages and noneof the vdisadvantages of similar bars formed bythe twisting together of two independent bars.-

y Other objects will be in part obvious from the annexed drawing 'and in 'part indicated in c0n.

nection therewith bythe following analysis of this invention. I

'I'his invention accordingly consists in the feature of construction,` combination of parts and in the unique relation of the members and the relative proportioning and disposition thereof, all as more completely outlined herein.

To enable others skilled in this art so fully to comprehend the underlying features thereof that they may embody the same by the numerous modifications in structure and relation contemplated by this invention, a drawing depicting a preferred form has been annexed to part of this disclosure, and in such drawing:

Fig. 1 Iis a plan view of a bar, formed in ac` cordance with this invention, before twist;

Fig. 2 is the same bar shown in Fig. 1 after it has been twisted; s

Fig. 3 is a cross-sectional view along the line III-III 0I Fig. 1?

Fig. 4 is across-sectional view along the line IV-IV 0f Fig. v2.

Figs. 1 and 3 illustrate a preferred shape of bar to be used in the present invention, before it is twisted. It is readily seen that this solid bar is formed of two outerl circular sections I and 3 l UNITED v"STAT-151s .PATENT OFFICE.

intermediate portion 2. Such a bar may be formed or shaped by any suitable method known to those skilled in the art, such as hot or cold rolling, drawing or any other method. The bar is then simultaneously twisted and stretched by clamping the ends 5 and 6 and twisting one end relatively to the other. 'I'his twisting and stretching is carried out until a substantial portion of the circular sections l and 3 are stressed beyond their elastic limit. It is important for the purposes of this invention that during the twisting operation the ends of the bar be fixed relatively to. one another in the longitudinal direction, sothatduring the twisting operating there will be no shortening of the bar and acsectional area. After the bar has been twisted,

itscentral section 7 between the clamped end portions 5 and 6 will have a shape substantially asshown vin Fig. 2.

As stated above, the effective transverse crosssectional area of the'twisted bar will be the same as 'that of the bar before twisting, despite the fact that there will be alengthening of the individual circular members making up the bar.

This will be apparent from a study of Figs. 3 and 4. Fig. 4 illustrates the circular cross-sectional area of the bar after twisting which will be seen to be the same as Fig. 3. Since during the twisting operation the bar las a whole is not permitted to shorten and therefore there will be the same amount of material between the fixed ends, the actual effective cross-sectional area of the entire bar will be exactly the same as before the twisting operation.

In order to increase the bond and prevent slip between the reinforcementbar and the concrete, the former may be provided with one or more ribs, such as indicated at 4. It will be seen that any deformation in the bar can be used for this purpose. The provision of transverse ribs 4, interconnecting the bars and webs, also serves to prevent rupture between the bars and web during the twisting operation, and thus permits the use of a. relatively small web and the positioning of a relatively larger amount of material remote from the axis of twist.

It will be obvious to those skilled in this art that the invention is not limited to the form of integrally interconnected together by a web or terconnected by a smaller amount of material Afig' lying in the axis. In other words, the type of bar contemplated is one which has a large amount of inertia about its central longitudinal axis, as compared with known bars of the same crosssectional area. Instead vof using two portions connected with another, a plurality of such portions, such as three or four can be used, and these portions need not be circular in shape, but may have any uniform cross-sectional shape.

The invention described above, will be seen to adequately fulll the objects primarily stated. As compared with 'reinforcing bars consisting of two bars twisted and stretched together, the bar fonned in accordance with the present invention will have-more effective bond surface, a higher modulus of elasticity and a higher compression value. As compared with-a single twisted bar of simple square or circular cross-section, the

. -present bar will permit the attainment of a high yield point with less actual stress upon the fibers ofthe bar. This results from the fact that the yield point of the entire bar is the average result of cold working the bar over .its entire crosssectional area. Since in the type of bar proposed by the present invention a greater amount of tained. The shape of the bar of the present inventionalso gives it a greater strength in compression than the usual'single solid bar.

It is. contemplated that the bar of the present invention will be made of the usual intermediate grade" reinforcing steel, although it is obviously not limited to fabrication by this material alone, but may be used with any suitable steels or alloys.

The stresses sct up in the bar of the present invenion are well within the breaking point of -the out-er fibers, and additional cold working such as bending can be done without reaching the breaking point.

Since a bar of the character oi' this invention has the stiffness of an I beam section, it will be stronger than the ordinary single bar or the bar formed by the twisting together of two independent bars. This increased stiiness permits it be laid in forms without sagging, while the irregularity of its surface permits it to be tied withi out slipping. v

Having described an illustrative embodiment of the invention, it is accordingly .pointed out that various changes and modifications therein are contemplated, without departing from the invention as set forth in the following claims.

I claim:

1. A twisted reinforcement bar, comprising two portions of substantially the same cross-sectional area. integrally interconnected by a web of lesser cross-sectional areauthan' either individual portion, said portions and =we b being'gtwisted as a unit about the longitudinal axis oi' the bar, and longitudinally spaced, relatively narrow transverse'ly extending ribs interconnecting said portions and said web.

2. A twisted reinforcement bar comprising two cylindrical portions of substantially the same cross-sectional area integrally interconnected by a web of a. lesser cross-sectional area, than either portion, said two portions and web being twisted as a unit about the longitudinal axis of the bar, and longitudinally spaced, relatively -narrow transversely extending ribs interconnecting said portions and said web. A

3. A reinforcement bar comprising a .plurality of portions of substantially the same crosssectional area equally spaced from and about a common longitudinal axis, means extending along and including said axis for 'integrally interconnecting said portions. said'means having a 'lesser cross-section-than any'of said portions, saidportions and connecting means being .twistedabout said axis as a4 unit .to form asingle -solidtwisted bar, and longitudinally spaced, relatively narrow transversely extending ribs interconneetinglsaid portions and said connectingmeans 4 4. A reinforcing member comprising a' plurality of longitudinally extending metal bars whose ad'- jacent longitudinal sidesalje integrally interconneeted by' a relatively narrow, web, the transverse cross-section of the whole reinforcing -member being such that more than ,half of the metal of each bar is spaced at a greater distance from the longitudinal axis ot themember, extending through the centerof the web, than the radius oi corresponding circular bars having the same total cross-sectional area as that of the whole reinforcing member, said bars being twisted about said axis to form a twisted reinforcing member, and longitudinally spaced, relatively narrow transverse ribs interconnecting said bars and said web to prevent rupture between said bars and said web during twisting.

JOSEPH D. s'rI'rEs. l

CERTIFcATE oF CORRECTION. A Patent No. 2,256,060. September 16, 19141. i

JOSEPH D. s'r'rxs.

It is hereby certified that error appears 1n the printed specification of the s bove'numbered patent. requiring correction as follows: Page 2, first nnlumn, line 2, for "amount" reed --moment; and that the said Letters Patxhculd be read wlth :E

:is currection therein that the same may conform 15u'.- recoxd of time case in the Patent Offfe.

miguel and Sealed una 211er: :my ef' :1er-:11,- A. D. 19142.

Henry- Van Arsdale, (Seal) Acting Commsslcner of Patents. 

